Seizure?

[muskrat]

Most boosters will give your plugs a orange colour, I try to stick to BP or Caltex and steer clear of the cheapies. With the modern fuel I run a little rich but also go 1 grade hotter in the plugs. Higher octane takes longer to burn so the timing is advanced a few degrees. High compression accelerates the combustion so if running the two std timing isn't too far out.
93 rich in a low comp motor at std timing shouldn't ping but wouldn't pull your arms out of their sockets. My 51 A7 has all my left over racing gear (alloy head, big valves, 357 cam, lecy ignition, 932 concentric etc) but with flat top pistons (7.5:1) running 98+ at 36 degrees BTDC. Surprises a lot of modern riders.
Cheers

[Shark]

The saga continues, after a couple of uneventful runs the old girl has done it again. This time I caught it before it locked the back wheel up and rolled off to the side of the road and let it cool. The pistons are scuffed and it will need to be bored but I  guess it could have been worse. It had high compression pistons that won't be replaced, if I want to play "boy racer" I will ride something else. When I figure how to upload a photo or two I will. Cheers.

[JulianS]

Always consider poor lubrication as a possible cause of seizure - obstructed oil feed  - check the feed pipe and filter -and/or poorly performing oil pump. Some pump to crankcase gaskets sold are made with oil holes far too small and reduce feed significantly. Engine then runs far too hot and you seize.

[Triton Thrasher]

Did you do anything about the mixture after the previous seizure? Or did you just decide that wasn't the problem?

How accurate is your 4 thou clearance?

[Shark]

JulianS, no I did not look at oil feed only return. Will look as considering an SRM pump.
TT, yes I lifted the needle one notch and had the timing checked and did some running and looked at plugs (new ones) and they looked the same as the old ones (rich). The slide I left as stock. The 4 thou bit came from the PO so how accurate that is who knows?

[Shark]

Ouch

[JulianS]

That is a seriously high compression piston - certainly more than the dome topped 9:1 used in the RGS. Look like the 10.5:1 which used to be available from Hepolite. No wonder the bike pinged!

[muskrat]

Yep, that's a10.5:1 similar to what's in my Cafe. Have to run at least 102 octane fuel or retard the timing to 30 degrees btdc on 95 octane to stop pinging.
Cheers

[bikerboy]

Powermax I seem to remember them being called I still have a brand new set in the garage somewhere

[BSA_54A10]

Yep. I had them too.
Ran Fleet 100 ( 102 octane ) + octane booster.
Impossible bike to start went like a bat out of hell
Ate clutch plates for breakfast but WGAF cause I could ride rings around most of what else was around

[Shark]

The old dear is back on the road again but have only done about 70 k's, it is much smoother and the engine note seems different with no clatter at all when at idle. Finish the running in and hopefully one happy boy. Thanks to all.